She was laid down at the Flender Werke in Lübeck as yard number 295, launched on 30 November 1941 and commissioned on 28 January 1942 with Kapitänleutnant Heinz Walkerling as commanding officer. Command was transferred to Kapitänleutnant Heinz Hungershausen on 20 April 1943.

She was a fairly successful boat, sinking over 26,000 tons of Allied shipping in a career lasting just 14 months and six patrols. She was a member of fifteen wolfpacks. After training with the 5th U-boat Flotilla, U-91 was assigned to the 9th flotilla on 1 September 1942 for operations.

Contents

Operational career[edit]

1st patrol[edit]

U-91 departed Kiel for her first patrol on 15 August 1942. Having negotiated the Iceland/Faroes 'gap', she was attacked by a US PBY Catalina on 1 September. (This incident was originally thought to have been against U-756).

The escort vessels of convoy ON 127 fired on the boat on 12 September; minor damage was sustained.

U-91 sank the Canadian destroyer HMCS Ottawa on 14 September. The boat fired two torpedoes at 02:05 and confirmed a hit. At 02:15, the submarine came across the damaged Ottawa once again, but mistook her for a different vessel and fired a third torpedo, which destroyed the ship, killing 114 of the 181 men aboard.[1]

2nd patrol[edit]

The boat's second foray started from Brest on 1 November 1942 and finishing there on 26 December. It was relatively uneventful.

3rd patrol[edit]

U-91 was subject to a "rain of aircraft bombs and depth charges from surface ships" which obliged her to break off an attack to carry out repairs on 21 February 1943.

The boat was soon back in action; on 17 March, U-91 attacked Convoy HX-229. Two American vessels - Harry Luckenbach and Irénée Du Pont - were destroyed along with the British merchant ship Nariva. The Luckenbach was hit by two torpedoes after five were fired between 03:37 and 03:41. The Luckenbach sank in a mere three minutes, with seventy-one of the eighty men evacuating in lifeboats, although there were no reports of them being rescued. Nariva and the Irénée Du Pont had been damaged by U-600 earlier that day. U-91 fired three torpedoes at 05:56: Two finishing off the Du Pont, a third crippled the Nariva.[2]

4th patrol[edit]

Sortie number four began from Lorient on 29 April 1943; it was also relatively quiet but terminated in Brest on 7 June.

5th patrol[edit]

U-91 was attacked by a B-24 Liberator of No. 10 Squadron RCAF on 26 October 1943. The undamaged U-boat had been searching for U-584 to supply her with fuel. The Liberator's assault was thought to have sunk U-420. A few days later, (on the 31st), having found U-584, she commenced the re-fuelling operation, but the two boats were spotted by aircraft from the escort carrier USS Card. In the ensuing mayhem, U-91 escaped without damage after diving; U-584 was not so lucky, she was sunk.

6th patrol and Loss[edit]

U-91 departed Brest for the last time on 25 January 1944; on 26 February she was sunk in the middle of the North Atlantic by depth charges from the British frigatesHMS Affleck, HMS Gore and HMS Gould.

36 men died with the U-boat; there were 16 survivors. Kapitänleutnant Heinz Hungershausen was not one of them.